The previous post was for PS2 games. Those would be the cheapest.
Personally I have been disappointed with the DS remakes (more $ for the same game). I would much rather play the originals on the PS2. Granted portability has its pluses but ...
For XBOX the best games were released recently so they would be more expensive. JAde Empire however can be found for under $10 and is an awesome game. Knights of the old republic and Baldur's gate are good choices too (original XBOX compatible with XBOX360).
Newer games that are pretty good, Tales of Vesperia, Fable 2, The last remnant, Lost odyssey, Infinite undiscovery.
Anyway, the question was for starter RPGs and my recommendation stands FFX, Grandia (1,2 or 3) or Star Ocean (2 or 3)
Grandia is on PS1
Star Ocean 2 is on PS1
FFX on PS2
Grandia 2 and 3 on PS2
Star Ocean 3 on PS2
